186 



14. C.furca, Ehr. ; Kent, I.e. p. 455, pi. 25, f. 31-32. Bergh. 

 1. c. p. 195, pi. 12, f. 1-3; pi. 13, f. 13-20. Gourret. Ann. 

 d. Mus. d'llist. Nat. Marseille Mem. No. 8, 1883, p. 45-47, 

 pi. iv., f. 58-59, 67-68. 



There seem to be two well marked forms, which may be regarded 

 as varieties of this species. Besides the typical form (Bergh. 

 figs. 13-20) there is the C. j^entayonum, Gourret, and its variety 

 rectum (pi. 4, f. 58-59), which are fairly constant in size, shape, 

 length of horns, and the strongly areolate cuirass. One of the 

 specimens which came under my observation had nearly the whole 

 of the areolate plates broken away, and there remained a rigid 

 homogeneous shell, having the same shape as those in wliicli the 

 plates were intact. This fact suggested to my mind two questions, 

 to which as yet I am unable to find answers : Is the cuirass 

 double ? or does the individual cast it off naturally when it is too 

 small, and secrete a larger one 1 



The forms described by Gourrett, under the following names, 

 C. dilatatum and its variety jmrviun, and C. ylohatuvi were well 

 represented in my gatherings, and seemed to be constant as to 

 length of horns, sculpture, tfec. ; the only noticeable variations 

 appeared to be iu the form of the body and the distance between 

 the posterior horns. In some specimens the body was well 

 rounded and the horns but a little distance apart ; others had 

 the body compressed and the horns widely separated, whilst many 

 examples had a deeply concave ventral surface, and the aspect of 

 the body when viewed from behind exhibited a cresentic outline, 

 with the horns closely approximate, and the dorsal surface 

 strongly convex. 



Obtained in tow-net off Green Point (very common). 



15. C. (jravidum, Gourret, 1. c. p. 58, pi. 1, f. 15. 



In the description of this species the (inferieure) anterior 

 portion of the body is described as globose. The specimen met 

 with by me had the body strongly compressed, otherwise it agrees 

 with the description and figure. 



Surface, off Green Point, P.J. 



16. C. trijjos, Mull.; Kent, I.e. p. 454, pi. 25, f. 24-33. Bergh. 

 1. c. p. 204, pi. 12, f. 4-6, pi. 13, tig. 21-27. Gourret, 1. e. 

 pi. 1, f. 1,2,3-7, pi. 2, f. 33-35. 



This is a very variable species, scarcely any two individuals 

 being found alike. The references given above indicate tlie 

 varieties observed. 



Very common in surface gatherings off Green Point, P.J. 



17. C. hirundinella, Miill. ; Kent, 1. c. p. 457 (C. longicorne), and 



p. 859, pi. 25, f. 26. Bergh. I.e. p. 215, pi. 13, f. 12. 

 Biitschli, 1. c. pi. 53, f. 9, a-b. 

 As far as I have been able to ascertain, this species has not 

 hitherto been found iu salt water. After a very careful examina- 



